The dominant spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative disorders characterized by incoordination of gait, limb, and eye movements, slurred speech and swallowing difficulties. Nine of the 11 known SCA mutations are microsatellite repeat expansions (Schols et al., Lancet Neurol 3, 291-304 (2004). In 1994, SCA5 was mapped to 11q13, a centromeric region with suppressed recombination (Ranum et al., Nature Genetics 8, 280-284 (1994). MRI and autopsy findings show cerebellar cortical atrophy, Purkinje cell loss and thinning of the molecular layer (Liquori et al., Spinocerebellar ataxia type 5 (SCA5) in Cerebellar Ataxias ed. M. Pandolfo, Cambridge University Press pp 445-450. in The Cerebellum and its Disorders (eds. Manto, M.U. & Pandolfo, M.) 445-450 (Cambridge University Press, Cambridge, 2002). Additional SCA5 families from France and Germany were reported with similar clinical and neuroradiological findings (Stevanin et al., Neurology 53, 1355-1357 (1999), and Burk et al., Neurology 62, 327-329 (2004)).
The significance of identifying ataxia genes provides an improved method for diagnosis of individuals with the disease and allows the possibility of prenatal/presymptomatic diagnosis for better classification of ataxias.